PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “AMINO ACID MIXTURES”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 523 records · Page 29Linked to original sources

Effect of two amino acid solutions on leucine turnover in preterm infants.

OBJECTIVE: To assess the effect of two different parenteral amino acid mixtures, Trophamine and Primene, on leucine turnover in preterm infants. METHOD: Leucine kinetics were measured with [5,5,5 D3]leucine tracer in 15 infants receiving Trophamine (group 'T') (mean birth weight 1,263 g) and 22 who received Primene (group 'P') (mean birth weight 1,336 g) during two study periods, within a few hours after birth but before introduction of parenteral amino acid solution, and again at postnatal day 7. The rate of appearance of leucine was calculated from the enrichment of alpha-ketoisocaproic acid in plasma. RESULTS: There were no significant differences in leucine turnover within a few hours after birth in the two groups. In the infants who received Primene leucine turnover on day 7 was significantly lower than in those who received Trophamine (269 +/- 43 vs. 335 +/- 27, p < 0.05). Despite a higher intake of leucine in the Trophamine group (108 +/- 10 vs. 77 +/- 8 micromol.kg(-1).h(-1)), leucine released from proteins at day 7 was higher in this group compared to Primene (227 +/- 27 vs. 192 +/- 42 micromol.kg(-1).h(-1)). CONCLUSIONS: Primene administration results in lower leucine released from proteins, an estimate of protein breakdown, than Trophamine in preterm infants. Increases in whole body leucine turnover in response to administration of i.v. amino acids is influenced by the composition of the amino acid mixture. The factors responsible for this difference remain to be elucidated.

Amino Acids↗

An introduction to nutritional treatment in inborn errors of metabolism--different disorders, different approaches.

Treatment of metabolic disease aims to restore homeostasis, where possible. This can be achieved in a number of ways. For disorders of intermediary metabolism, treatment involves a thorough understanding of the disorder and the pathogenesis of the deleterious effects The various approaches indicated may involve substrate restriction, replacement of deficient products, removal of toxic metabolites or stimulation of residual enzymes. Newer therapies include enzyme replacement and gene therapy. Often, the cornerstone of treatment is dietary. Substrate restriction includes not only a diet low in the substrate indicated by the disorder, but also strict calorie support in times of illness to avoid catabolism. Useful levels of substrate restriction may require the use of supplements of "medical foods", for example amino acid mixtures. Provision of the deficient products is important in disorders affecting energy metabolism. To understand the problems involved in nutritional treatment it is helpful to consider examples of different types of disorders. In Maple syrup urine disease (MSUD), treatment with a very strict low-protein diet, supplemented by a branched-chain-free amino acid mixture is successful, but each intercurrent illness is hazardous, regimens for sick days vital, and strict lifelong treatment is needed. Treatment for phenylketonuria is similar in restricting a substrate but there is no tendency for systemic illness if the phenylalanine levels are too high. Disorders of the urea cycle are difficult dietary challenges because while a very low-protein diet is required, no specific amino acid needs to be avoided and there is a fine line between adequate protein intake and chronic catabolism. Fatty acid oxidation disorders affect energy production and can be detected by newborn screening using tandem mass spectrometry. For long-chain fatty acid disorders, long chain fats must largely be avoided and medium-chain fats must be substituted while strictly avoiding catabolism. Glycogen storage disorders require strict attention to providing carbohydrate, at all times including throughout the night. Many patients with inborn errors do not need any specific dietary therapy, (eg those with storage or neurodegenerative disorders), although all children benefit from an optimal diet, and sick children need this especially.

Dietary Supplements↗

Amino acids and glucose differentially increased extracellular 5-hydroxyindoleacetic acid in the rat brain.

To reveal the role of serotonergic neurons in the regulation of feeding, the levels of 5-hydroxyindoleacetic acid (5-HIAA), a metabolite of serotonin, in the striatum and the hypothalamus were continuously monitored by an in vivo microdialysis technique. Intake of 20% casein diet did not induce significant changes in the 5-HIAA level in these regions. When rats were fed on 5% casein diet (83.5% carbohydrate diet) for 2 h, the level of 5-HIAA in the striatum gradually increased and reached a maximum (226 +/- 44% of basal level, M +/- SEM, n = 7) at 4 h after stopping the diet. In the medial hypothalamus, its level also increased to 183 +/- 19% (n = 10) at 2 h after starting the diet. On the other hand, a 60% casein diet increased the level of 5-HIAA in the lateral hypothalamus to 138 +/- 19% (n = 10) at 2 h after starting the diet. The intravenous infusion of each of these nutrients, glucose, amino acid mixture or lipid, produced more rapid elevation of the 5-HIAA level than oral intake of the diets. When rats were infused with glucose, its level in the striatum continued to be elevated. In the medial hypothalamus, glucose infusion increased 5-HIAA to the maximum (189 +/- 38%, n = 7) at 4 h after starting infusion. In contrast, serotonergic neurons in the lateral hypothalamus seemed to respond only to infusion of the amino acid mixture, and the level of 5-HIAA reached 163 +/- 14% (n = 5) of the basal level at 1 h after starting the infusion. These results suggest that rapid elevation of glucose or amino acids may independently stimulate serotonin metabolism in these brain areas, participating in the feedback regulation of nutrient intake.

Amino Acids↗

Influence of low magnesium concentrations in the medium on the antioxidant system in cultured human arterial endothelial cells.

Using cultured human endothelial cells, we investigated the contribution of concentrations of magnesium to the antioxidant system and oxidative stress. Cells were cultured at decreasing magnesium levels (569, 380, 190 and 95 microM) for 72 h. We then measured the amount of released hydrogen peroxide (H2O2) from the cells, the consumption of exogenous H2O2, the intracellular reduced glutathione (GSH) and the oxidized glutathione (GSSG) contents and the activities of glutathione reductase and catalase. Magnesium at a level of 949 microM was used as a control. The effect of magnesium deficiency on cellular membrane permeability was determined by measurement of the amount of [14C] amino acid mixture released from the cells. The results showed that during 72 h of magnesium-deficient treatment, the H2O2 release from the cells gradually increased and consumption of exogenous H2O2 was enhanced during the first 48 h of treatment. GSH content gradually decreased but GSSG was not affected. The activity of glutathione reductase was first stimulated and then inhibited. Catalase activity was gradually reduced. [14C]Amino acid mixture release from the cells continuously increased. We suggest that magnesium deficiency affected the intracellular antioxidant system in cultured endothelial cells.

Amino Acids↗

Long-term consumption of an amino acid diet reduces the pancreatic enzyme secretion response to a trypsin inhibitor in rats.

We investigated pancreatic enzyme secretion in response to soybean trypsin inhibitor (SBTI) in rats fed amino acids as a nitrogen source, from the fetal stage to adulthood. Pregnant rats were divided into two groups 4 d before parturition. During gestation and nursing, one group was fed a 15% protein diet (protein-fed rats) and the other (amino acid-fed rats) a 15% amino acid mixture diet that simulated the composition of the protein diet. Each male offspring was weaned at 4 wk after parturition and fed the same diet as fed to its dam for an additional 6 wk. Pancreatic amylase secretion in response to an intraduodenal infusion of SBTI (10 mg/rat) was observed in the protein-fed rats but not in the amino acid-fed rats. Amylase secretion in response to an intravenous injection of cholecystokinin (CCK) (10 ng/kg rat) was observed in both groups, and the magnitude of the response was significantly higher in the amino acid-fed rats than in the protein-fed rats. An increase in the level of plasma CCK in response to SBTI was observed in the protein-fed rats but not in the amino acid-fed rats. These results suggest that the long-term amino acid diet, because of its ability to inhibit the SBTI-stimulated CCK-releasing process in the small intestine of rats, reduced the pancreatic enzyme secretion response to a trypsin inhibitor. Six rats fed the amino acid mixture until 1 wk after weaning were fed the protein diet for the next 5 wk. These rats showed no pancreatic amylase secretion in response to SBTI, suggesting that dietary components around the weaning stage may affect the development of the ability of small intestinal cells to recognize a trypsin inhibitor.

Amino Acids↗

Cholesterol-lowering effects of soybean, potato and rice proteins depend on their low methionine contents in rats fed a cholesterol-free purified diet.

Rats were fed cholesterol-free purified diets containing casein, rice (RP), potato (PP) or soybean (SP) proteins having different amounts of methionine (25.9, 21.3, 16.2 and 10.9 g methionine/kg, respectively). Each protein was fed at 250 g/kg diet for 14 d. Growth rates of rats were the same in all groups. Serum total cholesterol concentrations were lower in rats fed SP, PP and RP than in those fed casein. Fecal bile acid plus neutral steroid excretion was significantly higher in rats fed the RP, PP and SP diets compared with those fed casein. There was a significant negative correlation between serum cholesterol concentration and fecal total steroid excretion (r = -0.490, P = 0.01). However, a stronger positive correlation was observed between serum cholesterol concentration and dietary methionine concentration (r = 0.674, P = 0.0003) or methionine:glycine ratios (r = 0.656, P = 0.0005). In a separate experiment in rats fed diets containing amino acid mixtures simulating the RP, PP and SP diets, serum total cholesterol concentrations were lower than in rats fed simulated casein. Fecal total steroid excretion was the same in all groups. A strong correlation was found between serum cholesterol concentration and dietary methionine concentration (r = 0.743, P = 0.0002) or the methionine:glycine ratio (r = 0.685, P = 0.0009) in rats fed the amino acid mixtures. Finally, we examined the hypocholesterolemic effects of 250 g SP or casein/kg diet with or without supplementation with 0.3 g/100 g sodium taurocholate (TC). Supplementation with TC did not alter the hypocholesterolemic effect of SP. These results support the view that RP, PP and SP lower serum cholesterol concentration in a similar manner.

Amino Acids↗

Control of hepatic proteolysis by amino acids. The role of cell volume.

1. Proteolysis in isolated perfused rat liver was monitored as [3H]leucine release into effluent perfusate after in vivo labeling by intraperitoneal injection of [3H]leucine about 16 h prior to the perfusion experiment. Exposure of the livers to hypotonic perfusion media (175-295 mOsmol.l-1) increased liver mass due to cell swelling and inhibited [3H]leucine release. The extent of inhibition of [3H]leucine release was linearly related to the liver-mass increase, regardless of whether livers from fed or 24-h-starved rats were studied. 2. Infusion of glycine (0.5-3 mmol.l-1) or glutamine (0.5-3 mmol.l-1) during normotonic perfusions (305 mOsmol.l-1) led to a concentration-dependent increase of liver mass and inhibition of [3H]leucine release. The inhibition of [3H]leucine release was again strongly dependent upon the increase of liver mass, regardless of whether cell swelling was induced by glutamine or glycine in normotonic perfusions, by exposure of the liver to hypotonic media or whether amino-acid-induced cell swelling was modified by the nutritional state. The effects of glutamine and glycine on [3H]leucine release were additive to the same extent as that found when the liver-mass increase was observed. 3. Alanine, serine and proline inhibited [3H]leucine release in parallel to the extent of amino-acid-induced liver-mass increase; however, the inhibition of [3H]leucine release was about twice that found when comparable degrees of cell swelling were induced either by hypotonic exposure or by addition of glutamine or glycine. The relationship between alanine-induced liver-mass increase and the inhibition of [3H]leucine release was also maintained in presence of aminooxyacetate (0.2 mmol.l-1). 4. Infusion of an amino acid mixture, roughly mimicking the concentrations found in portal venous blood, to livers from 24-h-starved or fed rats inhibited [3H]leucine release by 56.0 +/- 2.4% (n = 6) or 31.1 +/- 2.3% (n = 3), respectively, and increased liver mass by 5.0 +/- 0.1% (n = 6) or 2.2 +/- 0.3% (n = 3), respectively. Regardless of the nutritional state, there was a close relationship between the amino-acid-mixture-induced (and also phenylalanine-induced) increase of liver mass and the degree of inhibition of [3H]leucine release; however, the inhibition of [3H]leucine release was about fourfold higher than that found when comparable degrees of cell swelling were induced by hypotonic exposure.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗

In vitro culture of human peritoneal mesothelium for investigation of mesothelial dysfunction during peritoneal dialysis.

There is a growing need for more biocompatible peritoneal dialysis fluid formulations. Using a method of in vitro cell culture we have examined the effect of osmotic agents, antiseptics and drug additives on various functions of human peritoneal mesothelial cells (HPMC). We have demonstrated that glucose and amino acids reduce the HPMC proliferation rate in a dose-dependent manner. 3H-methyl-thymidine incorporation into HPMC exposed to either 1.1% amino acid mixture or 2.0% glucose was decreased to (mean +/- SD) 32.5 +/- 6.1% and 16.8 +/- 1.2% of the control level respectively. Cultured HPMC have been shown to produce a fibrinolytic activity which may be estimated by the rate of plasma clot lysis. This activity may be diminished following the pre-incubation with 2.0% glucose and 1.1% amino acid mixture. We have found that povidone-iodine exerts a dose-dependent cytotoxic effect towards HPMC as measured by the increased 86Rb or 3H-inulin release from radiolabelled cells. We have also demonstrated that insulin enhances the 86Rb uptake and stimulates the Na, K-ATPase activity in HPMC but on the other hand is capable of reducing the phospholipids secretion from HPMC. Glucose, hydrocortisone or verapamil have also been shown to inhibit the release of mesothelial phospholipids. These data indicate that the mesothelial cell culture provides a convenient model for testing the biocompatibility of peritoneal dialysis solutions and assessing the dysfunction of mesothelial cells during peritoneal dialysis.

Cell Division↗

Effects of aminooxyacetate, alanine and other amino acids on protein synthesis in isolated rat hepatocytes.

Protein synthesis in isolated rat hepatocytes has been measured by the incorporation of [14C]valine at high concentration and constant specific activity (5 mmol/l and 315 muCi/l). Protein synthesis was stimulated by the addition of an amino acid mixture, and by a number of individual amino acids alone, most notably alanine. Energy substrates (lactate, pyruvate) stimulated protein synthesis to the same extent as alanine, suggesting that a major part of the amino acid effect could be due to the provision of energy. Aminooxyacetate, an inhibitor of glutamate transaminases, inhibited protein synthesis strongly (70%), and abolished the stimulatory effects of alanine and energy substrates. This could indicate that hepatocytic protein synthesis is subject to positive control by a transamination-dependent agent.

Amino Acids↗

The lysosomal pathway of intracellular proteolysis in liver: regulation by amino acids.

The bulk of cellular protein in hepatocytes is sequestered and degraded by two classes of autophagy, (a) an overt or macro form, and (b) microautophagy. Macroautophagy is rapidly induced by amino acid deprivation and the administration of glucagon and suppressed by amino acids and insulin. Amino acids appear to be its primary regulator since liver perfusion studies have shown that it can be inhibited almost completely and proteolysis decreased from maximal (4.5% hr) to basal rates (1.7%/hr) by 4 times normal plasma amino acid concentrations. The resulting alterations in the aggregate volume of autophagic vacuoles are associated with proportional changes in the amount of cytoplasmic protein sequestered and in rates of protein degradation. Since the apparent turnover of autophagic vacuoles is 0.087 min-1, the pools of sequestered protein at all levels of macroautophagic stimulation are sufficient to account fully for the observed rates of accelerated rate of proteolysis. Microautophagy differs from the former in that the cytoplasmic 'bite' is smaller and it is not subject to acute physiological regulation. It is, however, dramatically decreased to near zero during refeeding after prior starvation. These and other findings indicate that it is adaptively regulated, possibly as a consequence of alterations in the amount of smooth endoplasmic reticulum. The amino acid control of accelerated protein degradation appears to involve direct inhibition by a small group of amino acids (Leu, Tyr/Phe, Gln, Pro, Met, Trp, and His) and the permissive action of alanine. Of unusual interest is the fact that, whereas the inhibitory amino acid group evokes responses identical to a complete amino acid mixture at 0.5x and 4x normal amino acid concentrations, it loses its effectiveness at normal levels; similar responses have been shown for leucine alone. The loss of effectiveness at normal concentrations is abolished by the addition of 0.5 mM alanine which by itself is not directly inhibitory. No other amino acid can replace alanine. These findings suggest a novel role for alanine that could be of importance in linking energy demands to proteolysis. A hypothetical model for proteolytic regulation by leucine and the other inhibitory amino acids is presented.

Amino Acids↗

Nitrogen sparing effects and mechanisms of branched-chain amino acids in the injured rat.

A series of experiments in a rat injury model were designed to elucidate the role and mechanisms of branched-chain amino acids in the post-injury catabolism. Our results suggest that: 1. Nutritional support can maintain nitrogen equilibrium in the early post-operative state. 2. Branched chain amino acids exert a nitrogen sparing effect and thus prevent or minimise post-operative catabolism. 3. Increasing the amount of infused branched chain amino acids results in nitrogen retention. 4. A balanced amino-acid mixture containing 45 per cent branched chain amino acids seems to be optimal for nutritional support in the post-injury state.

Journal Article↗

Further study of factors affecting amino acid incorporation into protein by isolated mitochondria.

1. The incorporation of amino acids into protein in isolated mitochondria has now been studied in more detail, and with mitochondria from a range of tissues. 2. Liver mitochondria from newborn rats are twice as active as those from adult rats. 3. The mitochondria are inactivated by excessive homogenization and repeated freezing and thawing. 4. The incorporation is sensitive to conditions of incubation and in particular to the rate of oxygenation, shape of vessel and depth of fluid. Best results are obtained by incubation in flat-bottomed vessels containing suspensions with less than 3mm. depth of fluid. 5. The requirement for oxidizable substrates has been examined with a range of substances, and most of the common energy-yielding metabolites of the mitochondrion are effective. Their activity is greatly influenced by concentration, and some, but not all, of the substrates show optimum concentrations for incorporation with decreased activity at higher concentrations. 6. Some amino acids can act as energy sources for the incorporation. 7. The effect of increasing the concentration of labelled amino acid is different for different amino acids, and complex effects occur on the addition of amino acid mixtures. 8. It is concluded that the amino acid incorporation into protein finally obtained is the result of many interacting factors related to the structural and metabolic state of the mitochondrion.

Amino Acids↗

Alterations in plasma and CSF amino acids, amines and metabolites in hepatic coma.

The dog with an end-to-side portacaval shunt (PCS) has been extensively used as a model to investigate hepatic encephalopathy (HE) as it demonstrates a plasma amino acid pattern similar to patients with chronic liver disease. In adult mongrel dogs, the effect of PCS on plasma and CSF amino acids, octopamine (OCT), phenylethanolamine (PEA) and CSF 5-hydroxyindolacetic acid (5-HIAA), were studied. Moreover, the effect of correction of plasma amino acids by infusional techniques was investigated.Tyrosine, tryptophan and phenylalanine levels increased dramatically during the development of HE in plasma and CSF, while valine, leucine and isoleucine decreased in plasma only, but CSF levels remained stable. Plasma and CSF octopamine and phenylethanolamine and CSF 5-HIAA increased markedly as clinical features in the dogs' behavior, characteristic of hepatic encephalopathy occurred, including hypersalivation, ataxia, flapping tremor, somnolence and finally coma. Once in coma, the dogs were infused with an amino acid mixture (F080) calculated to normalize the plasma amino acid pattern. After one to eight hours, the dogs began to awake. Simultaneously, blood, and CSF aromatic amino acids returned to their control values, as did OCT, PEA and CSF 5-HIAA. If F080 infusion was stopped, biochemical alterations would appear within one week, again accompanied by clinical hepatic encephalopathy.The results indicate that the altered levels of aromatic and branched chain amino acids, octopamine and PEA in plasma and CSF correlate well with the development of HE and that correction of the plasma amino acid abnormalities improves encephalopathy simultaneously with correction of neurotransmitter derangements in CSF.

Amines↗

[Problems of the amino acid content in the blood plasma and their absorption in the intestines in chronic lead poisoning].

As against controls essential differences in the amino acids content were disclosed largely in patients with a well-marked form of poisoning, i. e. a fall in the level of 7 from among 17 amino acid under examination (valine, glycine, leucine, lysine, serine, tyrosine, phenylalanine). After a peroral administration of 100 gm of an amino acids mixture the increment in the amount of amino acids in the blood of these patients proved lower than in controls both after a lapse of 30 and 60 minutes. In patients with a mild form of poisoning a fall of the serine, tyrosine and phenylalanine level in the blood was ascertained. The amino acids loading revealed a lesser accretion of amino acids in the blood on expiration of 60 minutes. The specific D-penicillinamine medication had no effect on the amino acids content in the plasma and their absorption in the intestines.

Adult↗

Symptomatic relapse in bulimia nervosa following acute tryptophan depletion.

BACKGROUND: Preclinical and clinical studies suggest that lowered brain serotonin neurotransmission may contribute to the pathophysiology of bulimia nervosa (BN). The aim of our study was to test this hypothesis by examining the psychological effects of a dietary-induced impairment in serotonin activity in subjects known to be at risk for manifestation of the clinical syndrome of BN. METHODS: An 85.8 g amino acid mixture lacking the serotonin precursor tryptophan and a balanced mixture were administered to 10 clinically recovered, medication-free female subjects with a history of BN in a double-blind, crossover design. Twelve healthy female subjects with no history of psychiatric disorder were studied as a comparison group. Observer and self-rated measures of mood and eating disorder cognitions were made for the 7 hours following administration of each amino acid mixture. RESULTS: Compared with healthy controls, subjects with a history of BN had significant lowering of mood, increases in ratings of body image concern, and subjective loss of control of eating following the tryptophan-free mixture. CONCLUSIONS: Our results suggest that diminished serotonin activity may trigger some of the cognitive and mood disturbances associated with BN. Our findings support suggestions that chronic depletion of plasma tryptophan may be one of the mechanisms whereby persistent dieting can lead to the development of eating disorders in vulnerable individuals.

Acute Disease↗

A comparison of intraduodenally and intracolonically administered nutrients on the release of peptide-YY in the dog.

The objective of this study was to compare the effects of various nutrients (fats, proteins, amino acids, and carbohydrates), given directly into the duodenum or the colon, on the release of peptide-YY (PYY) in conscious dogs. As reported previously, this study showed that plasma levels of PYY increased significantly (P less than 0.05) within 15 min in response to an oral mixed meal. Intraduodenal (ID) administration of a fatty acid (oleic acid; 100 mmol/L; 100 ml/h) stimulated a robust release of PYY, whereas ID administration of an amino acid mixture (phenylalanine plus tryptophan; 100 mmol/L each; 100 ml/h), glucose (1 g/kg), or a liver extract (10%; 100 ml/h) failed to elevate plasma levels of PYY. ID administration of glucose at 2 g/kg caused a mild but significant elevation in plasma PYY levels. Intracolonic administration of saline, a fatty acid, an amino acid mixture, glucose, or a liver extract significantly stimulated PYY release. This study suggests that as chyme moves from the stomach to the proximal bowel, fat is the primary constituent of food that stimulates the prompt release of PYY. However, unabsorbed nutrients can release PYY by a direct contact with the PYY-containing cells lining the intestinal lumen of the terminal ileum, colon, and rectum. Both mechanisms probably participate in the release of PYY.

Amino Acids↗

Effects of excess methionine ingestion on hepatic phosphate, adenine nucleotides and free amino acids in the rat.

Adult male rats were force-fed either a single dose of 200 mg of DL-methionine or an amino acid mixture with the pattern of casein. The animals were anesthetized with pentobarbital at 0, 1.5, 3 and 4 hours after intubation, and samples of liver were removed by a freeze-clamping technique at 0, 15 and 30 seconds of ischemia. Hepatic ATP, ADP, AMP, Pi, glucose-6-phosphate, glucose and certain nitrogenous compounds as well as plasma glucose were determined. After methionine was given by intubation, hepatic methionine and glutathione increased severalfold within 1.5 hours; cystathionine showed a transient rise at this time but returned to normal at 3 and 4 hours, when taurine was progressively increasing. Several nonessential amino acids decreased, suggesting that they may be utilized for energy. Methionine force-feeding did not modify the concentration of hepatic adenine nucleotides and probably did not change their turnover, as estimated from changes during ischemia. The level and production of Pi during ischemia was increased however. After force-feeding the amino acid mixture, hepatic methionine, cystathionine and taurine were unaffected, and glutathione increased only at hours 3 and 4; glycine and threonine were elevated by 1.5 hours. Hepatic adenine nucleotides, inorganic phosphate and glucose were not significantly affected by the feeding of amino acids by intubation.

Adenine Nucleotides↗

Influences of protein malnutrition on amino acid composition, trace metal elements and tensile strength of rat hairs.

We examined hair properties from determinations of diameter, amino acid composition, trace metal elements, and tensile strength of the hairs from protein-malnourished rats. The coarse or medium hair diameters of the experimental protein-malnourished rats had a tendency to decrease more than those of the control. Total contents of amino acids in the hairs had a tendency to decrease in the protein-deficient rats. Cystine content of rat hairs definitely decreased only in 5% wheat- and 5% rice-pattern amino acid mixture diet groups but not in 5% gluten diet and 5% casein diet groups. And many of the low-protein diet groups were significantly lower in methionine content than the control except for the 5% casein diet group. The Mg, Zn, and Fe contents in the hairs considerably increased in protein-deficient rats against the control. Tensile strength of coarse hairs in the experimental protein-malnourished rats was significantly lower than that of the control. The changes in amino acid composition of rat hair proteins are more likely to be influenced by various qualities of dietary protein or different compositions of amino acid mixtures in the diets at a similar dietary protein level. It should seriously be considered from our data whether the reduced cystine content in the hair can be regarded as an indicator of nutritional status.

Amino Acids↗